He chose not to save him from the trainwreck that he caused, yeah. I get what the writers were going for--Ra's sacrificed sure footing for a killing stroke, which is a cool little plot thing, but even then, in the earlier scene that it was referencing, Ra's didn't just leave Bruce to freeze to death after knocking the ground out from under him, lol. I mean, I guess Bruce might have pulled himself out but still.
Movie batmans have tended to stray from his rule a few times. He killed Jack Nicholson joker didn't he? Then batfleck...
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I put my heart and soul into my work and I fear I have lost my mind in the process